A number of prostheses are known from treating the formation of aneurysms in bifurcated body lumens. A typical previously known bifurcated prosthesis comprises a hollow tubular graft having a main section and first and second legs. During open surgery, for example, to repair an abdominal aortic aneurysm, the main section is sutured to the aorta below the renal arteries, and the first and second branches of the graft are sutured to the corresponding iliac arteries. Because surgical implantation of previously known prostheses poses a major risk of mortality, such surgery frequently cannot be performed on patients in poor health.
In attempting to overcome the drawbacks associated with surgically implanted grafts, a number of methods and apparatus have been developed to implant such grafts percutaneously. Kornberg U.S. Pat. No. 4,562,596, describes a bifurcated graft for intraluminal, percutaneous implantation. The graft comprises a hollow tubular main portion connected to a first leg and a shorter second leg. The main portion includes a plurality of barbs that impale the healthy tissue of the aorta to retain the graft in position. A drawback of such grafts, however, is the inability to provide a fluid tight seal at the ends of the graft. Without adequate sealing, bypass flow paths may develop between the graft and the tissue which may eventually cause rupture of the aneurysm.
Chuter U.S. Pat. No. 5,387,235 describes a bifurcated graft having a main portion connected to first and second legs. Each of the main portion and first and second legs includes a barbed self-expanding anchor ring that engages healthy tissue in either the aorta or the iliac arteries to retain the graft in position. A drawback of devices of this type, however, is that the diameter of the delivery system must be large enough to accommodate the combined diameters of each of the anchor deployment mechanisms. Thus, for example, it may not be possible to use the device described in the Chuter patent in patients having small diameter femoral arteries.
Yet another drawback of previously known bifurcated grafts is the difficulty encountered in pulling the legs of the graft into the branch vessels. While a number of prior art methods have been developed for accomplishing this task, these generally involve snaring a guide wire, either in the iliac artery or in the abdominal aorta, to place a guide wire for deploying the leg of the graft in the contralateral branch.
In view of the foregoing, it would be desirable to provide a bifurcated graft, and methods of implantation, that provide positive sealing between the graft and healthy tissue proximal and distal of the graft site.
It also would be desirable to provide a bifurcated graft, and methods of implantation, that enable smaller diameter delivery systems to be employed than heretofore possible.
It further would be desirable to provide a bifurcated graft, and methods of implantation, that enhance the ease with which the legs of the graft may be deployed in the branches of a bifurcated body lumen.